[Mk2] [Turbo] Wiring up amp genius needed!!!

[GAZ]

Is there anyone in the Northants area who could help. I've run out of ideas. I tried to wire up my amp but get all sorts of problems. Sub pops when changing track, picks up power steering noise as well.

HELP!!

[Ed]

Where are you mounting the amp is it in the frunk or in the cabin.

Ideally you want to mount it in the frunk. The reason for this is that you can keep the power and ground lead as short as possible and also you don't have to pass them through the firewall to the cabin.

Power for the amp should come direct from the positive terminal of the battery with a correctly rated fuse just before the amps positive terminal. Ground for the amp should be wired direct to the negative terminal of the battery.

By wiring this way you avoid introducing a ground loop which is what you have at the moment. Most of the time when you get pops coming from the sub it is down to badly earthed ground wires.

As for the power steering noise this could be down to how you have set up the positive and negative leads for the amp or it could be down to your RCA leads and either how you have routed them or the shielding or lack of on the leads themselves.

Ideally you want leads that are double or triple shielded you also need to make sure that they are not lying next to part of the wiring loom else this can help to introduce electrical noise.

HTH Ed

[GAZ]

Thanks Ed

I have wired the amp to the battery including the ground. The RCA cables do not have shielding and not sure if they are double or triple shielded. They amp wiring kit cost £30.

I wired it from the frunk into cabin. Not really sure what I should be keeping the wires away from in order to reduce noise.

Did you have any trouble with yours?

[Ed]

I have no troubles from at all. If the whole amp kit including rca leads cost £30 then that could be most of your problem. I paid £20 per RCA lead for triple screened leads, similar to these.

You should be able to get away with double screened cables that will set you back around £10 - £15 a cable.

When routing the cables from the frunk through the firewall to the cd player use the rubber grommit that can be found on the right hand side of the car above and to the right of the negative terminal on the battery.

You should only need about 2 or 3 meters of RCA cable, the shorter the better. You don't want loads of excess cable coiled up in the frunk.

The other thing to consider is the quality of speaker wire and how you route it to your speakers.

Ed

[GAZ]

I'll be off to get some this weekend then!! The speaker wire wasn't very expensive either just standard stuff but quite thick. I routed them through the grommit you mentioned. Is it ok to have speaker & RCA cables in same grommit? What about the amp turn on lead?

Not sure which to keep seperate.

[Ed]

You can route all those wires through the grommit as long as the rca cables are shielded otherwise if they are cheap then they will pick up interference.

For the speaker wiring I used a good Oxygen Free Copper(OFC) speaker cable.

The amp turn on lead is just a standard 5 amp (I think) rated piece of wire.

I didn't cable tie all opf these cables together. I kept the RCA and speaker cables seperate as much as possible. The only place they are close together is when they pass through the grommit. If you wanted to be extreme you can route the RCA cables through the grommit in thefirewall above and to the left of the positive battery terminal(you'll find it under the brake master cylinder and brake booster). Then route the speaker cables through the other grommit I mentione above.

Ed

[un1eash]

It may be worth trying to mount the earthing point somewhere on the chassis and not the battery itself. Sometimes the remote wire can pick up interference, i had this problem when i had a switch on the remote wire.

[Gouda]

I had a very similar problem with my install recently, turns out it wasn't the RCA leads or the new speaker cables I ran throughout the car. It was a bad ground on the black wire (ground) from the back of the head unit.
I cut the existing wire, put a crimp on it and screwed it directly to an un-used nut on the chassis behind the head unit. This solved the problem.

The RCA cables I used I made my self and were not of exceedingly good quality nor were the connectors I used on either end. Think they were £1.99 gold plated craplins (maplins) jobbies and the cable was from memory about £2/meter.

PS. I have also bolted the ground (black) wire from the amps directly to the chassis, not the battery. I have also added an extra wire from the negative terminal of the battery to the chassis (in a differnt position) in the front of the car as there wasnt one there origionaly.

Hope this helps,

Gouda,

[GAZ]

Thanks mate
I'll give that a go because I'm still having problems. I'll let you know if it solves it.

[midenginedmaniac]

Agree with above. Must try to earth all audio components to a good source including the headunit. Straight to the battery is not always good. Keep power away from Signal. If you have to cross them do it at 90 deg.

[C-Jay]

I have 3 amps in my 2. One behind the passenger seat to run the subs and 2 in the boot to run the speakers. I have all connected to the positive battery with the grounds bolted to the chassis. I mounted them by removing an exixting bolt and placing the wire there then screwing it back up. Very easy to do...just dont try tighten too hard as old bolts like to break.

Also, with your sub. Connect your positive wire from your amp to the negative of the sub and vice versa with the negative wire. Should give you some better quaility bass.

Good luck with it

C Jay

[Paul R]

Havent read all this thread - but sounds like you need to mount the earth as close to the amp as possible, not to the battery.

Cheers,

Paul.

[mrbriggs]

Where in the firewall do people feed the cables through? I have just got an amp and finding it hard to get the cables through! Or do I have to drill a new hole and stick a grommit in?

Thanks all.

[johnnymr2]

Straight to the battery is not always good.

because.........????

the -ve terminal of the battery is where you are referencing to and so is the ideal place to pick up the 0v from, the chassis is connected to the battery and so all you are doing its finding a return path via the chassis, its not like the runs are long in a 2 and if they were then you would just increase the CSA of the -ve cable.

[Vindezal]

how do i get rid of interference cackle on the radio from the engine bay?

My amp is mounted in the frunk.

[johnnymr2]

have a look at the route that the cables are taking and try to seperate the signal from the power, also could try using an RF supressor, basically a cap and a coil across the i/p

[midenginedmaniac]

Its all to do with earth loop impedances and ground loops. All audio items need to have the same resistance to earth or current will be allowed to run between them causing noise.

Straight to the battery is not always good as it may be too good an earth as the stereo, amp ariel etc in a 20 year old car may not have a good earth.

[johnnymr2]

Straight to the battery is not always good as it may be too good an earth as the stereo, amp ariel etc in a 20 year old car may not have a good earth.

am i the only person who rewires the HU when i do an install

[midenginedmaniac]

Do you rewire the ariel as well. And insulate the stereo cage from the chassis ?.

Dont forget the induced noise as well as the direct noise.

[johnnymr2]

Do you rewire the ariel as well. And insulate the stereo cage from the chassis ?.

Dont forget the induced noise as well as the direct noise.

Dont have the electric aerial looks wrong, mk2 doesnt have a cage but no i havent insulated it as the loom has been rewired to go direct to the battery, shortest return path. and how much induction will be picked up across this run????